The proposed project is in response to PAR-12-197, Improving Diet and Physical Activity Assessment. We are primarily interested in developing and applying innovative statistical methods to assess or correct for measurement errors in physical activity and dietary intake data. We are motivated by physical activity measurement issues involved in the Nutrition and Exercise in Women (NEW) study, conducted from 2005 to 2009. The NEW study was a 12-month randomized, controlled trial using a 4-arm design to compare the effect of three lifestyle-change interventions (dietary weight loss, moderate-to-vigorous intensity aerobic exercise, or both interventions combined) versus control (no lifestyle change). Specific foci of this proposal include: (i) To develop and apply methods in the generalized linear model to adjust for measurement error in physical activity and dietary intake data when their quantiles are used as covariates. (ii) To develop and apply methods in survival analysis to adjust for measurement error in physical activity and dietary intake data when their quantiles are used as covariates. (iii) To develop and apply methods to adjust for measurement error in longitudinal physical activity and dietary intake data when replicates are not available. The proposed models and methods will be applied to the physical activity data of the NEW study, and the Women's Health Initiatives (WHI). Furthermore, the methods developed in the proposal will have general applications to other studies of physical activity and dietary intake data.